Refrigerator



Dec. 14, 1948. L. J. BRONAUGH ET AL 23,058

REFRIGERATOR Original Fild Feb. 16 1931 INVENTOR; Lllironacug BY f[. POttT ATTOR NEY Reiaued Dec. 14,

UNITED s'rATEs PATENT OFFICE REFRIGERATOR Lewis J. Bronaugh, Portland, reg., and Thomas I. Potter, New York, N. Y., assignors, by direct and mesne assignments, to Refrigeration Patents Corporation, Buffalo, N. Y., a corporation of New York Original No. 2,058,165, dated October 8, 1936, Se-

rial No. 516,032, February 18, 1931. Application for reissue June 18, 1948, Serial No. 33,878

4 Claims. (Cl. 82-118) This invention relates generally to the art of refrigeration, and particularly to a new form of refrigerator.

The main object of this invention is the design of a refrigerator which will make it' possible at one and the same time and over long or short periods of time to perform several highly desirable tasks, namely to form ice or freeze desserts quickly, to provide cold storage for frozen meat and food stuffs, and to provide storage for food at temperatures above freezing.

The second object is to construct a cabinet in I which the ice-making or freezing unit is thermally insulated from the food storage department.

The third objectis the construction of a refrigerator which is not a compromise between a heat pumping apparatus to meet the various requirements of the present-dayhousehold.

The sixth object is to adapt the refrigerator to the rapidly increasing practice of buying the food stuffs in frozen form, and uninterruptedly maintaining this frozen condition until the food isprepared for use.

The seventh object is to eliminate completely all defrosting and objectionable drying out of the foods.

The eighth oblectis to make it possible for the householder to utilize all of the advantages obtainable from varying degrees of refrigeration heretofore only possible in large commercial plants.

Before entering into a description of this invention it must be understood that while mechanical refrigeration has many advantages over the ice caliy-d'efrosted is unsuitable for thepreservation of this class of food.

Again, there are, generally speaking, two classes of food which are put into a refrigerator; first,

food requiring merely to be kept coo1--that is, above freezing, and in most cases having a relatively high rate of evaporation. Second, food having a relatively low rate of evaporation and which should be maintained sis-temperatures well below freezing. In addition to this, comes the ever increasing demand for the ability to form ice and freeze desserts quickly.

It follows that the designer of a refrigerating machine soon finds himself compromising between a quick freezing machine and one which is best adapted for the storage of food. If the temperature of the food storage compartment falls too low as the result of an attempt to provide quick freezing the consequence is a rapid drying out of the food. To offset this certain manufacturers provide a cover for the food to prevent its drying out and impose upon the user the necessity of frequently adjusting the controls to obtain the kind of refrigeration desired. It is easily seen that an adjustment of controls to suit varying conditions (several of which may exist at the same time) does not solve the problem. In the refrigerator about to be described no adjustment of controls is necessary.

These, and other objects. will become more apparent from the specification following as illustrated in the accompanying drawing, in which:

Fig. 1 is a vertical section taken along the line I-l in Fig. 2.

Fig. 2 is a vertical section taken along the line 2-2 in Fix. 1.

Fig. 3 is a perspective view of the cabinet. Fig. 4 is a section taken along the line 4-4 in Fi 2.

' similar numbers of reference refer to similar parts throughout the several views.

Referring in detail to the drawing, there is shown a cabinet having four separate and distinct compartments contained within an outer box used by our ancestors. it has many limitations casing I 0. These consist of a chamber or compartment I l,. a freezing compartment l2, a cold storage compartment l3 and a food storage compartment It. The chamber or compartment ll contains any desirable form of heat pumping unit which. in this instance, includes acompressor Ill which is belt driven by a motor I. There is also provided the usual receiver I1 and condenser ii. The freezing compartment i2 is preferably a brine tank and includes suitable freezing trays I9.

Adjacent to the freezing compartment I2 is a cold The freezing compartment or brine tank, contains an expansion coil 22 whichwill be referred to as a freezing coil, and which is provided with the expansion valve 23. The coil 22 draws refrigerant from the receiver Il through the high pressure refrigerant line 24. 'The food storage compartment I4 is provided with a cooling coil 26 which draws refrigerant from the discharge of the freezing coil 22 and returns same throughthe pipe 28 to the compressor II.

The compartment Il may have any number of divisions and shelves 21 and contains a drip'collecting shelf 28 by means of which condensed moisture from the cooling coil 25 is collected and drained through an outlet 2!, either into a container It (as shown) or into a waste pipe. The food storage compartment Il contains a temperature-actuated motor controlling switch II which is placed in the motor circuit 82 and is set to operate the compressor. it whenever the temperature of the food storage compartment rises above the desired temperature, which, in this case, will be assumed to be forty degrees. The expansion valve 22 is set to permit a flow of refrigerant into the freezing coil 22, which will provide a temperature approximating zero, while the temperature in the cold storage compartment II will be in the neighborhood of twenty degrees.

These relative values are of course dependentv upon the various controlling factors and are given only to permit a clearer understanding of the invention and the objects attained thereby. Any

suitable insulating material 33 is employed in the construction of the cabinet, and the compartment II and combined compartments I2 and ii are provided with doors II and I5 packed with insulation material.

The requisite difference of temperature between the cooling compartment II and the cold storage compartment l3, can be maintained with the greatest economic efficiency by not only providing a proper ratio of the cooling elements for said compartments, but also by providing a proper relation of the insulation of the two compartments. 'It will be understood that there is no such thing as a perfect heat insulator and that a certain amount of heat is always flowing into a refrigerator compartment from the surrounding atmosphere (provided, of course, that the surrounding atmosphere is warmer than that of the refrigerator compartment). A heat insulator may thus be more properly termed a "heat impedance" because all it does is to retard the flow of heat and the rate of heat ilowthrough a heat insulator of given quality and thickness depends upon the temperature head. Since very low temperatures are to be maintained in compartments I2 and II it is important that they be thoroughly heat insulated. In other words, the heavier the insulation the better and the only limitation to the efliciency of such insulation is that imposed by questions of bulk, and expense. As shown in the drawing, compartments I2 and I3 are separated from the outside atmmphere by thick rear and side walls 38 and also by a thick door I! so that the heat flow into said compartments is reduced to a minimum. Since the chamber II under the compartments I2 and I It contains the apparatus for pumping heat out of t e re r serator. this compartment would naturally be warmer than the outside atmosphere and consequently a wall 38 is provided which is even thicker than the walls 38 to insulate the chambers against heat pumped into and generated in the compartment II. The temperature drop between the cooling compartment II and compartments I2 and II is comparatively much smaller and hence a thinner wall 40 furnishes suiilcient resistance to heat flow into compartments I2 and II out of compartment ll. The walls ti and door I separating the cooling compartment it from the outside atmosphere are thinner than the walls it and door 3|. as

shown. This difference of wall thickness is provided not as a measure of economy but because it is desired to maintain a higher temperature bers.

in compartment Il than in compartments l2 and it by permitting a greater heat flow into compartment II.

As indicated above it makes no difference how low the temperature falls in chambers 12 and II, but the range of temperatures permissible in compartment i4 is more critical. Foods kept in compartment ll must not be frozen and the moisture saturation point of the air in compartment It should not be lowered to such an extent as to dry out the foods; hence it is important to hold the temperature in said compartment well above the freezing point and yet low enough to prevent the food therein frmn spoiling. We have found that a temperature of about 40 Fahrenheit is very satisfactory under most conditions; but some other normal temperature may be selected provided it is above the freezing point, Whatever the temperature selected, it is obvious that it should be maintained without any great degree of variation and for this reason the control of the heat pumping system is preferably made to depend upon the temperature in the chamber H and the thermostat ii is placed in chamber ll rather than either of the other cham- If the insulation of chamber II were as heavy as that of the other chambers the temperature in the compartment I4 might remain for along period unvaried and in the meantime the temperature might be raised considerably in chambers It and I2, by opening the door 35 or by introducing warm foods therein; without in the least affecting the thermostat Ii and hence without operating the heat pumping unit. Thus the temperature ratio between the several compartments would be disturbed and could not be restored until the heat pumping unit was restarted.- Since. however, the insulation separating chamber it from the outside atmosphere is so proportioned that the rate of ambient heat flow into chamber I4 is greater than into chambers I2 and I l, the intervals between operations of the heat pumping unit-is reduced and thus 'more frequently are the relative temperatures of the several chambers reestablished. It will be understood, of course, that because of the series connection of the cooling elements the heat will be pumped out of compartments I2 and II through the cooling element 25 so that said compartments must be reduced to the desired temperature before the compartment I 4 will be chilled sufliciently for the thermostat 8| to stop the operation of the heat pumping plant.

While'the thermostat 3i controls the temperature of the compartment ll the setting of the expansion valve 2! controls the temperature of saute compartments i2 and i3. As the expansion valve is adjusted to restrict the discharge of refrigerant the pressure differential in the refrigerant circuit is increased, lowering the temperature of the coil 22 and that of-compartments. l2 and II, until they reach their respective minima, corresponding to the valve setting. The refrigerant will be completely vaporized in coil 22 until the temperatures of the compartments near said minima, when some of the refrigerant will reach the coil 25 in liquid form, and, by vaporizing therein, will c001 compartment H. Thus, by our system the compartments i2 and i3 must first be cooled to minima fixed by the setting of the expansion valve before compartment it can be cooled to a minimum set by the thermostat. This arrangement whereby one temperature is controlled by a thermostat and another by an ex,- pansion valve is a novel feature of our invention.

By proportioning the insulation to offer greater resistance to inflow of heat into the cooling compartment i4" than into the cold storage compartment ii, a more uniform temperature can be obtained in the latter compartment. Were the insulation of the two chambers of the same heatresistant quality and thickness, the rate of inflow into the cold storage compartment would be greater, by reason of the greater temperature drop between the outside atmosphere and the cold storage compartment than between the outside atmosphere and the cooling compartment. The heat pumping unit," after pulling down the temperatures of the two compartments to their respective predetermined heat levels would then be stopped by actuation of the thermostat in the cooling chamber. Thereafter, the temperature in the cold storage chamber would climb faster than that in the cooling chamber because of the greater head of ambient heat impressed on the insulation of the cold storage chamber. Hence, there would be a marked rise in temperature in the freezing compartment before the temperature in the cooling compartment would rise sufficiently to actuate the thermostat. Thisdifficulty we have overcome by proportioning the heat impedance of the walls to the heat head they must oppose and while such proportioning results incidentally in economy of material, it has for its primary object to maintain a more uniform tem-- perature in the cold storage compartment as well as in the freezing compartment which is thermally connected therewith.

From the foregoing it will be seen that there is provided a refrigerator having a non-frosting food storage compartment in which food may be held at desirable temperatures without .undue evaporation. Secondly. that quick freezing for ice and desserts is ever available. Thirdly, that there is provided uninterrupted cold storage at freezing temperatures, and lastly, that the necessity for regulating the control system is entirely eliminated since a wide range of temperatures is provided simultaneously, andfur'ther, that not only is the necessity for defrostin eliminated entirely, but also the evaporation of the food stuffs is reduced to a minimum.

The articles placed in the cold storage'compartment are those not giving off much moisture. and whatever moisture does find its way into the cold storage compartment, either by evaporation or by openingthe door thereof, will be deposited as snow rather than as ice, due to the low temperature prevailing in the compartment it. In other words, there is no objectionable frosting in the cold storage compartment, for the reason above stated, and no frosting in the cooling com-- partment since the temperature maintained there is above freezing. There may, of course, occur a slight amount of frosting where the cooling coil 25 enters the compartment ll.

Another factor of great value found in this arrangement resides in the fact there the more the cooling compartment is used the greater will be the efficiency of the cold storage and freezing compartments.

By arranging the compartments as illustrated with the cooling chamber H which is the one most used, at the top of the cabinet, access may be had to this compartment without stooping, while the intermediate compartments l2 and II are also elevated by placing them above the compartment i I, so that the various food chambers are arranged to provide maximum convenience in actual service.

What is claimed is:

1. A. household refrigerator which in normal operation provides above-freezing moist cold air for preserving in 'a refrigerated condition foods susceptible to moisture loss by evaporation and below-freezing dry cold air and a dry cold surface for preserving foods in a frozen condition, said refrigerator comprising a cabinet having a cooling compartment and a freeaing'compartment,

thermal insulation around said compartments thermally insulating said compartments from each other and from the outside atmosphere, air in said cooling compartment having a substantial- 1y stable temperature of about 40 F. and having a. humidity whose relative value is at least at 32 l3., air in said freezing compartment having a temperature well below 32 F., a cooling refrigerant expander having heat-conducting surfaces within said cooling compartment and constructed and arranged to maintain its heat-conducting surfaces at a temperature above 32 F. while with drawing heat from said compartment, to maintain said air in said cooling compartment at said substantially stable temperature, a freezing refrigerant expander having heat-conducting surfaces within said freezing compartment and constructed and arranged to maintain its heat-conducting surfaces at a temperature well below 32 F. while withdrawing heat from said compartment, volatile refrigerant in said expanders, a single liquefying unit associated with said expanders and constructed and arranged to condense refrigerant expanded by heat extracted by said expanders from both said compartments, the volatile refrigerant circulating through said expanders being the sole heat-extracting medium, and a thermostat responsive to the temperature in one of said compartments controlling the operation of said llquefying unit.

2. A household refrigerator which in normal operation provides above-freezing moist cold air for preserving in a refrigerated condition foods susceptible to moisture loss by evaporation and below-freezing dry cold air and a dry cold surface for preserving foods in a frozen condition, said refrigerator comprising a cabinet having a cooling compartment and a freezing compartment, thermal insulation around said compartments thermally insulating said compartments from each other and from the outside atmosphere, a cooling refrigerant expander having heat-conductin surfaces within said cooling compartment and constructed and arranged to maintain its heat-conducting surfaces at a temperature above 32 F. while withdrawing heat from said compartment, whereby air in said cooling compartment is some cooled thereby to a temperature above 32' land is maintained at" a humidity whose relative value is at least 100%it 32' 1".', a freezing refrigerant expander having heat-conducting surfaces within said freezing compartment and constructed and arranged to maintain its heat-conducting surfaces at'a temperature well below 32 1". while withdrawing heatfrom said compartment whereby in said freezingcompartment is cooled thereby to atemperaturewell below32 R, volatile refrigerant in said ex'panders, a single liquefying unit associated with said expanders and constructed and arranged'to condense refrigerant expanded by heat extracted from both said compartmerits, the 'volatile' refrigerant circulating through said 'f'expanders being the sole heat-extracting mediilm, and a thermostat responsive to the temperature in one of said compartments controlling the operation of said liqueiying unit.

3. A= household refrigerator which in normal operation'provides above-freezing moist cold air for preserving ina refrigerated condition foods susceptible to moisture loss by evaporation and below-freezing dry cold air'and a dry cold surface for preserving foods in a frozen condition, said refrigerator comprising a cabinet having a cooling compartment and a freezing compartment, thermal insulation around said compartments thermally insulating said compartments from each other and from' the outside atmosphere, air in said cooling compartment having a substantially stable temperature whose value is about 40 F. and having a humidity whose relative value is at least 100% at 32 F., air in said freezing compartment having a temperature well below 32 F., a' cooling refrigerant expander having heat-conducting surfaces within said cooling compartment and-"constructed and arranged to maintain its heat-conducting'suriaces at a temperature-above 32F. while withdrawing heat from saidcompartment'to maintain said air in said cooling compartment. at said substantially stable temperature, a freezing refrigerant expander having -heat=conducting surfaces within said freezing compartment and constructed and arranged to maintain its heat-conducting surfaces at altemperature'well below 32 F. whilewithdrawing heat from said compartment at its temperature well below 32 F., volatile refrigerant in said expanders, a single liquefying unit associated with said expanders and constructed and arranged to condensemefrigerant expanded by heat extracted by said expanders from both said compartments, the volatile refrigerant circulating through said expanders being the sole heatextracting medium. a thermostat responsive to the temperature in said cooling compartment and controlling the on-oil' cycles of saidliquefying unit in response to variation of said temperature, and the thermal insulation around said cooling compartment offering less resistance to flow of heat thereto from the outside atmosphere than does the thermal insulation of the freezing compartment to insure starting of said liquefying unit by heat flow into said cooling compartment during an of! cycle of said liquefying unit before the temperature in said freezing compartment approaches a non-freezing value.

4. A household refrigerator which in normal operation provides above-freezing moist cold air for preserving in a refrigerated condition foods susceptible to moisture loss by evaporation and below-freezing drycold air and a dry cold surmidity whose relative value is at least 100% at 32 F., a freezing refrigerant expander having heat-conducting surfaces within said freezing compartment and constructed and arranged to maintain its heat-conducting surfaces at a temperature well below 32 F. while withdrawing heat from said compartment whereby air in said freezing compartment is cooled thereby to a temperature well below 32 F.. volatile refrigerant in said expanders, a single liquefying unit associated with said expanders and constructed and arranged to condense refrigerant expanded by heat extracted from both said compartments, the volatile refrigerant circulating through said expanders being the sole heat-extracting medium,

.a thermostat responsive to the temperature in said cooling compartment and controlling the on-oii! cycles of said liquefying unit in response to said temperature, and the thermal insulation around said cooling compartment offering less resistance to flow of Heat thereto from the outside atmosphere than does the thermal insulation of the freezing compartment to insure starting of said liquefying unit by heat flow into said cooling compartment during an ofi cycle of said liquefying unit before the temperature in said freezing compartment approaches a non-freezing value.

LEWIS J. BRONAUGH. THOMAS I. POTTER.

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